check for error code 600 and print error message

add filter tests

tests/test_filter.py

@@ -0,0 +1,30 @@
+"""Unit tests for the filter command in the OBS WebSocket CLI."""
+
+from typer.testing import CliRunner
+
+from obsws_cli.app import app
+
+runner = CliRunner(mix_stderr=False)
+
+
+def test_filter_list():
+    """Test the filter list command on an audio source."""
+    result = runner.invoke(app, ['filter', 'list', 'Mic/Aux'])
+    assert result.exit_code == 0
+    assert 'Filters for Source: Mic/Aux' in result.stdout
+    assert 'pytest filter' in result.stdout
+
+
+def test_filter_list_scene():
+    """Test the filter list command on a scene."""
+    result = runner.invoke(app, ['filter', 'list', 'pytest_scene'])
+    assert result.exit_code == 0
+    assert 'Filters for Source: pytest_scene' in result.stdout
+    assert 'pytest filter' in result.stdout
+
+
+def test_filter_list_invalid_source():
+    """Test the filter list command with an invalid source."""
+    result = runner.invoke(app, ['filter', 'list', 'invalid_source'])
+    assert result.exit_code != 0
+    assert "No source was found by the name of 'invalid_source'" in result.stderr